Abstract
In this study, the callus of Carica papaya was treated with silver nitrate solution to form silver nanoparticles which were later used as anti-contaminant substances in micropropagation media on C. nocturnum (cestrum, night queen) and Rosa indica (rose) in tissue culture medium. For this purpose, the rose and cestrum explants were cultured using murashige and skoog (MS) media containing 2 mg/l benzylaminopurine (BAP). After micropropagation of the shoots, different concentrations of biogenically synthesized silver nanoparticles (AgNPs) i.e., 2, 3, and 5 ppm were added into the MS media, for dose optimization. The morphology of tissue-cultured plants in control and experimental has been studied and compared through fluorescent microscopy and Scanning Electron Microscopy (SEM). The cells, tissues, and vascular bundles of C. nocturnum and rose tissue culture plants were studied in both control and treated plants. AgNPs added at a concentration of 5 ppm to the tissue culture medium of both test plants were safe and effective in controlling the contamination and the bacterial and fungal attack in the tissue culture medium was reduced; it gave the highest percentage of survived plants in both the rose and the cestrum plant. No significant difference was observed in the chlorophyll content of the plants maintained on treatment medium having AgNPs concentration of 5 ppm and the control plants maintained on medium without nanoparticles. The molecular assessment of the stress impact of AgNPs treatment was analyzed through expression of the SAND and PP2A housekeeping genes in treated plants and control plants by comparing their mRNA profile on real-time PCR, and the results showed equal expression of SAND and PP2A in both the control and treated plants. This study proves that low amounts of bio-synthesized silver nanoparticles when supplied in tissue culture media can act as an anti-contaminant in rose and cestrum in vitro cultures without affecting its morphology, physiology, and genetics.